A Queens man was stabbed in the heart last night while trying to rescue his little brother from a group of knife wielding thugs on a J train platform.

Dario Paiva, 27, raced to his brother Khristian’s side after the younger man was beset by four attackers near the 85th Street-Forest Parkway station, only to meet his doom.

The Woodhaven man was fatally stabbed around 11:30 p.m. after confronting his brother’s attackers on the subway platform. He was pronounced dead on arrival at Jamaica Hospital. No arrests have been made.

Khristian Paiva, 19, was on the phone with his mom Norma Paiva around 11:20 p.m.

“I’m on my way home,” Khristian told his mom.

That’s when the gang, who had apparently been arguing with a girl on the street, approached Khristian, with one of the attackers allegedly proclaiming: “I’m mad, I’m going to do something, I don’t give a f—-.”

Overhearing the dispute through the phone, Norma Paiva sent Dario to help his brother. By the time, the Kingsborough Community College student arrived, the gang had fled into the elevated subway station.

Dario Paiva, who was studying to be a lawyer and intended to transfer to Queens College, which Khristian attends, insisted on following the group so the brothers could identify them for cops.

“My brother is very protective of me,” Khristian Paiva told The Post. “He was worried if they saw me again they would attack me.”

When Dario Paiva tried to confront the gang, all four pulled knives and rushed at the brothers, Khristian Paiva claimed.

“My brother was pushing me and he got stabbed once, in the heart,” a weeping Khristian said. “I called emergency services. The lady told he me how to do CPR but he died, he died in my arms.”